Determination of true stress-strain data behond the necking point and fracture loci of vintage steel pipes, using digital image correlation and finite element analysis

使用数字图像相关和有限元分析确定老式钢管颈缩点和断裂位点后面的真实应力应变数据

• 批准号: 490975-2015
• 负责人: Weck, Arnaud
• 金额: $ 2.62万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=618360
• 关键词: Determination; true; stress; strain; data

Manufacturing, transportation, power generation and many other industries strongly rely on a high supply of oil and gas products. Pipelines are the main means of transportation and delivery of these vital products. However, like any structural system, they are vulnerable to through life damage and degradation. Depending on many factors, pipeline industry has defined and standardized a wide variety of assessment and inspection techniques to consider the integrity of their systems. Generally, the significance of features (e.g. dents, cracks, wrinkle and buckles) and metal loss (e.g. corrosion) determine the severity of the maintenance period to assure a safe integrity for the system. In recent years, particular interest was aimed at vintage (manufactured before 1970) steel pipe materials to investigate their micro- and macro-structural behaviors to large deformations, under different loading conditions (such as uniaxial tension, compression and bending). The consideration of large deformations/displacements in a pipeline system could result in the generation of large strains in the pipe material. Normally, very large strains (beyond the uniaxial necking point) exist in regions with features such as wrinkle or local buckling. These high levels of induced strains can lead to damage accumulation in the pipe and endanger the integrity of the pipeline system. In order to obtain better pipeline deformation predictions, feeding more reliable material properties to an FE model is of great importance. The main purpose of this work is to conduct uniaxial tensile testing, using a Digital Image Correlation (DIC) technique, to obtain Lankford coefficients, stress-strain curves over a large range of strains (beyond the necking point), and the fracture strains for different stress-triaxialities (fracture locus). In order to consider the material anisotropy, tests will be conducted for a variety of vintage steel pipe materials at two different pipe orientations, axial and circumferential. The effect of sample size on the resulting mechanical behavior will also be investigated.

制造、运输、发电和许多其他行业强烈依赖石油和天然气产品的大量供应。管道是这些重要产品运输和交付的主要手段。然而，像任何结构系统一样，它们很容易受到终生损坏和退化。根据许多因素，管道行业定义并标准化了各种评估和检查技术，以考虑其系统的完整性。一般来说，特征（例如凹痕、裂纹、皱纹和弯曲）和金属损失（例如腐蚀）的重要性决定了维护周期的严重程度，以确保系统的安全完整性。近年来，人们特别关注老式（1970 年之前制造）钢管材料，以研究其在不同载荷条件（例如单轴拉伸、压缩和弯曲）下大变形的微观和宏观结构行为。考虑管道系统中的大变形/位移可能会导致管道材料产生大应变。通常，非常大的应变（超出单轴颈缩点）存在于具有皱纹或局部屈曲等特征的区域。这些高水平的诱发应变会导致管道中的损坏累积并危及管道系统的完整性。为了获得更好的管道变形预测，将更可靠的材料属性输入有限元模型非常重要。这项工作的主要目的是使用数字图像相关（DIC）技术进行单轴拉伸测试，以获得兰克福德系数、大范围应变（超出颈缩点）的应力-应变曲线以及断裂应变不同的应力三轴度（断裂轨迹）。为了考虑材料的各向异性，将对各种老式钢管材料在两个不同的管方向（轴向和周向）进行测试。还将研究样本大小对最终机械行为的影响。